1. Field of the Invention
Various embodiments of the subject invention relate to tool retainers and tool retainer systems and, more particularly, to wear and retention sleeves for supporting and retaining a cutting tool within a support member.
2. Description of the Invention Background
Over the years, man has designed a variety of different tools for cutting materials. One such tool is employed in the mining of underground materials such as coal and the like. The tools, commonly referred to as “cutting bits”, are affixed to rotating cutting drums located on mining machines. As the cutting bits are advanced into the material to be mined, the cutting bits dislodge the material from the seam to enable it to be collected on a conveyor arrangement for removal from the mine. Each such cutting bits commonly has an elongated cylindrical shank portion that is received in a mounting block that is attached to the driven cutting drum. A replaceable cutting insert, fabricated from hardened material, is usually affixed to the end of the cutting bit. In many applications, wear sleeves are employed to support the cutting bit within the support member and to reduce the wear experienced by the support member resulting from continuous operation.
A variety of bit retainer methods and systems have been designed. Examples of such retainer arrangements are disclosed in U.S. Pat. No. 3,767,266 to Krekeler, U.S. Pat. No. 4,084,856 to Emmerich et al., U.S. Pat. No. 4,484,783 to Emmerich, U.S. Pat. No. 4,575,156 to Hunter et al., U.S. Pat. No. 4,836,614 to Ojanen, U.S. Pat. No. 4,850,649 to Beach et al., U.S. Pat. No. 5,088,797 to O'Neill, U.S. Pat. No. 5,302,055 to O'Neill, U.S. Pat. No. 5,725,283 to O'Neill, U.S. Pat. No. 6,357,832 to Sollami, and U.S. Pat. No. 6,623,084 to Wasyleczko.
FIGS. 1-5 illustrate a prior method of retaining a cutting bit 100 within its respective support member. The cutting bit 100 commonly includes a cutting tip or insert 102 that is attached to a conical portion 104. The cutting insert 102 is usually fabricated from hardened material and is attached to the end of the conical portion 104 by brazing or other conventional fastening methods. The cutting bit 100 further has an elongated shank 106 which is cylindrical in shape and designed to be supported in a tool holder block or support block 120 that is attached to a rotatable cutting drum 124 which is operably supported on a mining machine (not shown). As is common practice, when the rotating cutting bit 100 is brought into contact with the material to be mined, the cutting tip 102 of the cutting bit 100 dislodges the material from the seam to enable it to drop onto a conveying system for removal from the mine.
A flange 107 is formed on the end of the cutting bit shank 106. The flange 107 is sized to enable it to be inserted into a shank-receiving hole 122 in the support block 120. See FIG. 2. A retention sleeve 130 is placed over the shank 106 such that it extends between the flange 105 of the cutting bit 100 and the retainer flange 107. An axially extending slot 132 is provided in the sleeve 130 to permit the sleeve 130 to be installed on the shank 106. The retention sleeve 130 is commonly fabricated from steel. The cutting bit 100 is then typically installed into the support block 120 by hammering the end of the cutting bit to cause the shank 106 and sleeve 130 to be inserted into the shank-receiving hole 122 in the support block 120 until it is seated as shown in FIGS. 1 and 2.
Such prior retention sleeve arrangements can be difficult to install. In particular, to attain sufficient retention, prior retention sleeves must be sized in such a manner relative to the shank-receiving hole in the support block such that when they are fully inserted into the shank-receiving hole, a sufficient amount of retention forces are generated. Thus, when installing such prior bit and sleeve arrangements, the sleeve and bit assembly must be hammered into the shank-receiving hole. This requires the installer to support the shank and sleeve assembly adjacent the hole opening with one hand and strike the end of the bit with a hammer or other tool to force it into the shank-receiving hole. Often times the installation takes place in cramped quarters further complicating the installation process and exposing the installer to injury should the hammer inadvertently miss the bit and strike the installer's other hand that is supporting the bit adjacent the hole opening. Further, while being difficult to install, the retention forces (i.e., the amount of force required to press the sleeve and bit out of the hole in the support block) attained by such prior arrangements are not high (i.e., commonly on the order of 100 to 120 pounds).
Furthermore, when using many prior wear sleeve arrangements that are pressed fit into a bore in a support block, the diameter and the total roundness of the bore are critical. If the diameter of the bore is too small, the sleeve could only be installed with great difficulty, if at all. In extreme instances, a bore that was too small may actually result in the sleeve becoming deformed or otherwise damaged which could result in damage to the bit shank. Such arrangements may also be difficult to remove. In many prior arrangements, the support block is heat treated and then machined to attain a bore with a very precise diameter. Such processes can be expensive and time consuming.